Visualizing Sound With Fluids

After a brief foray into the realm of visualizing sound through fire I decided to head in the other direction and watch vibrations propagate through some different kinds of fluids. I used water and a corn starch solution to get what I thought were some pretty cool results.

Step 1: Materials

Materials:
- Speaker (That you don't intend to use again...)
- Driver for the speaker (I had one laying around but you can build your own, use a guitar amp, etc)
- Plastic lid that is about 4'' - 6'' in diameter with about a 1/2'' lip to contain the fluid
- Corn Starch
- Water
- Hot Glue Gun
- Wire strippers, electrical tape, etc.
- Clear Plastic wrap (this is optional but when using corn starch it can replace the lid and just cover the speaker for some cool results)
- Frequency generator (I just used a program called AudioTest that I downloaded to my computer)

Step 2: Preparing the Speaker

Essentially this device is just a lid glued to a speaker. This will allow the vibrations from the speaker to be transfered directly into whatever fluid is in the lid allowing us to observe patterns. The other part of the setup is wiring the speaker to the driver. This part of the process will differ depending on what setup you have but is should be pretty straight forward. I would recommend cutting wires long enough so that your speaker can sit on the table and be far enough to not splash any water on the sensitive electronics. 

Step 3: Running the Setup With Water

To use this device simply pour water into the lid and play some sounds out of the speaker. If you play a slow sweeping wave you might be able to find out at which frequencies the fluid resonates as their will be a well defined pattern. The fun part of this is experimenting and changing up these frequencies to produce cool patterns in the water allowing you to visualize sound. 

Step 4: Running the Setup With Corn Starch

Running the setup with corn starch is definitely more fun than watching the water! When mixing corn starch with water I found that a 2:1 cornstarch to water ratio yields good results. The important part is to make sure that the cornstarch resists sudden stirring motions. This is what characterizes this mixture as a non-newtonian fluid. I found that the corn starch responds better at lower frequencies and higher amplitudes when compared to the water. Another thing that I tried was removing the lid and placing plastic wrap over the speaker. Then pouring some cornstarch onto the plastic wrap. This allowed the cornstarch to bounce around more on the speaker cone and was pretty entertaining to watch. You can also experiment with trying to get the tentacles of corn starch to crawl up your fingers and adding food coloring for some more fun!